Technical Field
The present invention relates to the technical field of straw composting, and particularly to a method for directly preparing a fertilizer by using straws, and a prepared straw organic fertilizer.
Related Art
About 1.5 billion tons (on the basis of dry matter) of crop straws and residues from cereal crops, vegetables and fruit trees are annually produced in China. These plant materials contain 60-75% of organic matter, 0.6-1% of nitrogen, 0.5-0.7% of phosphorus (P2O5), 1-1.2% of potassium (K2O), and also a variety of micro-elements essential to plants. If all these crop straws are returned to fields, 20-30% of the chemical nitrogen fertilizer, 40-50% of the chemical phosphorus fertilizer, about 50-60% of the chemical potash fertilizer and 70-80% of the micro-nutrient fertilizer can be saved, and the contents of soil organic matter in China can be significantly increased. It can be seen that the crop straws are a very valuable fertilizer resource, and it is particularly important and urgent to make full use of these straw resources under the strategic situation that the CPC Central Committee and the State Council recently put forward in terms of the double reduction of fertilizers and pesticides.
However, with the rapid development of China's economy and the large transfer of rural labor force, as well as the difficulties in farming and the problems of more serious pests and diseases in the next season crops caused by directly returning the crop straws to the fields, the practice of traditional returning of crop straws directly to the fields becomes more and more unsuitable, considering the current situation in the rural regions and in the agricultural production of China. In the harvesting season for crops, although governments at various levels and in various regions send a large number of persons to crop fields to ban burning of straws, burning of straws on the field sites is still very common, because there is no operable ways of straw use. The problem of straw burning cannot be solved fundamentally only by banning it forcibly.
In the past decade, straw-based power generation becomes very hot, and straw-based power generation plants at various scales are built throughout the country. However, because the straw has a low energy value and generally needs to be sun-dried before being received by the power plant, the storage and sun-drying of the straws greatly increase the cost. These directly lead to a dilemma in which although the straw-based power generation sounds very attractive, the actual operation is very difficult. It is a matter of wasting money and manpower to maintain the straw-based power generation by relying on government subsidies, in which it cannot run long. Therefore, to develop a practical and feasible way of straw resource utilization is a very urgent issue facing the agricultural production in China.
During the process of straw composting, although the straw is rich in organic matter and some nutrients, it is difficult for the composting microorganisms to acquire nutrients suitable for their growth in a short time (24 hours or 48 hours) such that the composting microorganisms can decompose the straw rapidly (the composting temperature rapidly rises to 60° C. in 48 hrs) because of the high C/N ratioin straws. However, if the added composting microbial strains cannot grow rapidly in a short period of time (5-7 days), failure of the microbial strains is caused, which is the frequently occurring insignificant effect of the composting microbes in starting the composting. Therefore, the development of a nutrient formulation with which the straw composting microorganism can start the decomposition of the straw is critical to the success of straw composting. The present inventors find through research that if only the composting microbial solution and water are added, the composting temperature rises quite slowly, and the temperature of the straw compost only reaches 49° C. at day 6, which may lead to the insignificant effect of the composting microbes in starting the composting.